Čoh, M. et al.: KINEMATICS OF USAIN BOLT’S MAXIMAL SPRINT VELOCITY Kinesiology 50(2018)2:172-180 KINEMATICS OF USAIN BOLT’S MAXIMAL SPRINT VELOCITY Milan Čoh1, Kim Hébert-Losier2, Stanko Štuhec1, Vesna Babić3, and Matej Supej1 1University of Ljubljana Faculty of Sport, Slovenia 2University of Waikato, Faculty of Health, Sport, and Human Performance, Adams Centre for High Performance, New Zealand 3University of Zagreb, Faculty of Kinesiology, Croatia Original scientific paper https://doi.org/10.26582/k.50.2.10 UDC: 796.42:577 Abstract: This study investigated the maximal sprint velocity kinematics of the fastest 100 m sprinter Usain Bolt. Two high-speed video cameras recorded kinematics from 60- to 90-m marks during the men 100 m final at the IAAF World Challenge Zagreb 2011, Croatia. Despite a relatively slow reaction time (194 ms), Bolt won in 9.85 s (mean velocity: 10.15 m/s). His fastest 20-m section velocity was 12.14 m/s, reached between 70- and 90-m marks, by 2.70 m long strides and 4.36 strides/s frequency. At the maximal velocity, his contact and flight times were 86 and 145 ms, respectively, and vertical ground reaction force generated equalled 4.2 times his body weight (3932 N). The braking and propulsion phase represented 37% and 63% of ground contact, respectively, with his centre of mass (CoM) exhibiting minor reductions in horizontal velocity (2.7%) and minimal vertical displacement (4.9 cm) emerged Bolt’s maximal sprint velocity and international predominance from his coordinated motor abilities, power generation capacities, and effective technique. This study confirms that his maximal velocity was achieved by means of relatively long strides, minimal braking phase, high vertical ground reaction force, and minimal vertical displacement of CoM. This study is the first in-depth biomechanical analysis of Bolt’s maximal sprinting velocity with the segmental reconstruction. Key words: 100 m sprint, athletics, biomechanics, sport performance, sprint running Introduction literature has attempted to explain Bolt’s perfor- Usain Bolt is one of the greatest athletes in mance using spatio-temporal parameters (Graubner the history of athletics. He is the winner of eight & Nixdorf, 2011; Maćkała & Mero, 2013), math- Olympic gold medals, as well as the world record ematical and biomechanical models (Beneke & holder in the 100 m (9.58 s), 200 m (19.19 s), and 4 x Taylor, 2010; Eriksen, Kristiansen, Langangen, & 100 m relay (36.84 s). During the 12th International Wehus, 2009; Graubner & Nixdorf, 2011; Taylor & Association of Athletics Federations (IAAF) World Beneke, 2012), as well as anthropometrical charac- Championships in Berlin in 2009, he established a teristics (Charles & Bejan, 2009; Maćkała & Mero, new 100 m world record with a tailwind of 0.9 m/s, 2013). There has also been attempts to estimate beating his previous world record by 0.11 s that Bolt’s 100 m sprinting potential (Barrow, 2012; had been set in 2008. Specifically, his 100 m world Eriksen, et al., 2009), with a general consensus that record was one of the most remarkable achieve- he could have run below 9.5 s if only his reaction ments in sprinting and was the largest improvement time had been better and under optimal environ- in the 100 m world record yet observed (Graubner mental conditions (i.e., tailwind and high altitude), & Nixdorf, 2011). Recently, at the 15th IAAF World thus agreeing with the prediction by Denny (2008) Championships in Beijing, 2015, Bolt managed to that humans can run 100 m in 9.48 s. However, kine- maintain his world titles in the 100 m, 200 m, and matic data of Bolt running in competition are rare, 4 x 100 m relay despite participating in few compe- and a more detailed investigation for Bolt’s whole- titions prior to the Championships due to injury. body kinematics could assist in verifying some of Bolt’s performance has been a subject of the numerous theories of his sprinting success. numerous media analyses, debates, and discussions, When Bolt set his current 9.58 s world record, as well as biomechanical investigations. Research his fastest 20-m section time was 1.61 s, reflecting 172 Čoh, M. et al.: KINEMATICS OF USAIN BOLT’S MAXIMAL SPRINT VELOCITY Kinesiology 50(2018)2:172-180 a mean velocity of 12.42 m/s (Graubner & Nixdorf, In a first instance, the videos from the sports 2011)1. This value is the highest absolute velocity broadcasters were used in conjunction with those ever reached by a sprinter during a 100 m race, from our cameras and the official race results to and the fastest mean velocity (10.60 m/s) over that count the total number of strides taken and to race distance. Bolt’s superior sprinting performance compute the mean velocity, stride length, and has been attributed to a strong acceleration phase, stride frequency of each competitor. Bolt’s data higher maximal velocity, advantageous power were compared to his fellow competitors and to his generation ability, and impressively long strides data available from previous races (Arribas, 2012; associated with his physical built (Beneke & Taylor, Hommel, 2009; Maćkała & Mero, 2013). Secondly, 2010; Graubner & Nixdorf, 2011). the instance of Bolt’s maximal sprint velocity Bolt participated in the IAAF World Challenge reached was isolated (~85 m) and relevant kine- Zagreb 2011, Croatia. Our team of scientists had matic parameters were extracted over the fastest the opportunity to further study the fastest sprinter 20-m section of his (70 to 90 m). For data extrac- in the world. The specific aim was to investigate tion, the computer program APAS (Ariel Perfor- the kinematic parameters associated with Bolt’s mance Analysis System, Ariel Dynamics Inc., Coto maximal sprint velocity during the men 100 m de Caza Trabuco Canyon, USA) was used to recon- finals. struct a 2D full-body biomechanical model using 16 reference points (Winter, 2005), which included the Material and methods metatarsals; the ankle, knee, hip, shoulder, elbow, and wrist joints; and two head markers. The coor- The IAAF World Challenge in Zagreb, Croatia, th dinate data from these 16 points were smoothed was held on September 13 , 2011, at the Sports Park using a low-pass second-order Butterworth digital Mladost. Prior to this observational research project filter with a 14 Hz cut-off frequency and used to with a case study design, permission to record video define 15 segments and the centre of mass (CoM) footage of the men 100 m sprint final was granted by of the model according to standard anthropometric the Technical Delegate and Organizing Committee tables (Winter, 2005). Although the 300-Hz data of the European Athletics Association. The temper- capturing frequency was used to determine flight o ature on the day of the competition reached 23 C, and contact times, video digitization was performed and there was a head wind of 0.1 m/s during the at 100 Hz to reduce redundancy and manual labour. event (IAAF, 2011). The primary athlete of interest The joint position accuracy was estimated to < 2 cm was Usain Bolt (age: 25 years, height: 1.96 m, in the sagittal plane based on the resolution of the weight: 86 kg; country: Jamaica). The other final- system, measurement area, and typical manual digi- ists were Kim Collins (35 years, Saint Kitts and tization error. Nevis), Richard Thompson (26 years, Trinidad and The running stride (distance from foot strike to Tobago), Jaysuma Saidy Ndure (27 years, Norway), foot strike of the same foot) was divided into the Mario Forsythe (25 years, Jamaica), Justin Gatlin ground contact (time of foot strike to toe off) and (29 years, the United States), and Ivory Williams flight (time of toe off to foot strike) phases for both (26 years, the United States). the left and right leg. The ground contact phase To record kinematic data from Bolt running, was further divided into the braking and propulsion two high-speed digital cameras (EX-F1, Casio phases according to the horizontal position of the Computer Co., Ltd., Tokyo, Japan), sampling at 300 CoM in reference to the ankle (braking: the CoM Hz with a pixel resolution of 720 x 576, were strate- is in front of the ankle joint; propulsion: the CoM gically placed along the track to capture data from is behind the ankle joint), and included an instance the 100 m sprint. Prior to the race start, two refer- of maximal amortization coinciding with the ence frames (dimension: 2 m x 2 m x 2 m) were used maximal knee flexion. From the digitized videos, to calibrate the final section (60 to 90 m) of Bolt’s the following kinematic parameters were extracted lane. The calibration procedure considered eight to describe Bolt’s mechanics during his fastest 20-m points from the two reference frames. Furthermore, section: stride length; stride frequency; ground to accurately quantify the sprinting dynamics of all contact time; flight time; braking time; propulsion seven competitors, an additional high-speed camera time; CoM height; CoM’s horizontal and vertical was placed closer to the start of the race and video velocities during braking, propulsion, and maximal footage from the six official sports broadcasters amortization; horizontal displacement of the CoM televising the event were acquired. The official during ground contact; distance between the foot reaction and finishing times of all sprinters were and the vertical projection of the CoM at the ground acquired from the IAAF results of the IAAF World contact; foot-CoM angle (angle formed using a line Challenge Zagreb 2011. connecting the CoM to the metatarsal relative to the 1 In the same biomechanical analysis of the 12th IAAF World Championships, Bolt’s maximal velocity was reported to be 12.34 m/s, reached at the 67.90-m mark of the race.